Grade 6 Science: The Energy and Simple Machines Questions Learners Miss Most
From August to October 2026, learners on Emerald answered about 100 Grade 6 Science practice questions. Only about 4 in 10 of those answers were right, one of the lowest results in our log. For comparison, Grade 3 Science answers in the same period were right more than 8 times in 10.
That's a small sample (one term, a few dozen learners), so treat it as a pointer rather than a national statistic. But the wrong answers are telling. When we looked at which choices learners picked, the same few misunderstandings came up again and again. This post goes through them, using real questions from Emerald's Grade 6 bank.
1. Energy transformations: say where the energy ends up
Most of the misses were on energy transformation questions, the kind tagged Quarter 3 in our bank.
When you plug a transistor radio into an outlet and switch it on, the electrical energy is turned into ____. A. Heat energy · B. Sound energy · C. Light energy · D. Radiant energy
Every learner who met this question got it wrong. Most picked heat, a few picked light. The answer is B, sound energy.
Why the mix-up? A radio does get a little warm, and it may have a small light. But the question asks what the radio is for. Its job is to turn electricity into sound. Small amounts of heat are a by-product of almost every device, so "heat" is rarely the best answer unless heating is the device's purpose.
The same idea, reversed:
Which energy transformation occurs in an electric iron? A. Heat to light · B. Light to heat · C. Heat to electricity · D. Electricity to heat
Learners who missed this chose C, heat to electricity. They had the right two words in the wrong order. The answer is D, electricity to heat: the iron uses electricity and produces heat.
A habit that fixes both: write the transformation as an arrow, input → output, before you look at the choices. - Radio: electrical → sound - Electric iron: electrical → heat - Phone speaker: electrical → sound - Plucked guitar string: mechanical (movement) → sound - Flashlight: chemical (battery) → electrical → light
Ask two questions: What goes in? (what you plug in, wind up, push or burn) and What is it for? (what you'd miss if it stopped working). The first is the input, the second the output.
2. Simple machines: match the definition word for word
Simple machine questions were the second big group. Learners often knew the names but matched them to the wrong descriptions.
Which simple machine is a sloping surface that reduces the force needed to lift something? A. Lever · B. Pulley · C. Wheel and axle · D. Inclined plane
Learners who missed this picked wheel and axle. The answer is D, inclined plane. The key words are sloping surface: a ramp.
It is any rigid bar that is free to rotate about its axis or fulcrum. A. Pulley · B. Lever · C. Wedge · D. Inclined plane
Wrong answers here were inclined plane and wedge. The answer is B, lever. The key words are rigid bar and fulcrum, the pivot a lever turns on.
Here's a one-line definition for each of the six simple machines, with the word to listen for:
| Machine | Listen for | Everyday example |
|---|---|---|
| Lever | bar + fulcrum (pivot) | seesaw, bottle opener |
| Wheel and axle | wheel turning a rod | doorknob, pencil sharpener crank |
| Pulley | rope over a wheel | flagpole, well bucket |
| Inclined plane | slope / ramp | wheelchair ramp |
| Wedge | two slopes meeting at an edge, splits things | knife, axe |
| Screw | inclined plane wrapped around a rod | jar lid, bolt |
One more from the bank:
Which does not belong to the group? A. Crank of a paper sharpener · B. Meat grinder · C. Doorknob · D. Spoon
Two out of three learners picked the sharpener crank. But the crank, the meat grinder handle and the doorknob are all wheel and axle machines, so the odd one out is D, the spoon. When a question asks "which does not belong", first find what the other three share.
3. Living together: mutualism vs. commensalism vs. parasitism
In a coral reef, clownfish and sea anemones live together. Which type of relationship is shown? A. Commensalism · B. Mutualism · C. Parasitism · D. Predation
Learners who missed this chose parasitism or commensalism. The answer is B, mutualism: the anemone's stinging tentacles protect the clownfish, and the clownfish cleans the anemone and drives away fish that eat it. Both benefit.
A quick way to sort these: score each partner as + (helped), 0 (unaffected) or − (harmed).
| Relationship | Partner 1 | Partner 2 | Example |
|---|---|---|---|
| Mutualism | + | + | clownfish and anemone; bees and flowers |
| Commensalism | + | 0 | barnacles on a whale |
| Parasitism | + | − | lice on a dog |
| Predation | + | − (eaten) | eagle and snake |
If you can say what each partner gets, you can name the relationship.
4. Plants: "what do they have in common?"
Ferns, conifers and angiosperms (flowering plants) have common characteristics. What are these? A. They produce seeds · B. They reproduce through spores · C. They have fibro-vascular bundles · D. They bear flowers
Both learners who missed it chose spores. That is true of ferns, but not of conifers or flowering plants, which make seeds. And only angiosperms bear flowers. What all three share is C, vascular tissue (xylem and phloem in "fibro-vascular bundles"), which carries water and food through the plant.
For "in common" questions, test each choice against every item in the group. One counter-example is enough to rule a choice out.
5. Space: which telescope uses radio waves?
A special telescope that can see images of objects with the aid of radiation. A. Hubble Space Telescope · B. Optical telescope · C. Radio telescope · D. Spectroscope
Learners picked Hubble, the most famous name. The bank's answer is C, radio telescope, which collects radio waves (a kind of radiation) from space instead of visible light. Familiar names are tempting; read the description, not just the choices.
How to practise these
- Say the answer before you read the choices. For energy questions, write "input → output" first. For machines, name the shape you're picturing.
- Read every choice to the end. Most wrong answers above were "almost right": the right words in the wrong order, or true for one item but not all.
- Do a few questions a day rather than a lot at once. Short daily practice beats a long session the night before an exam.
You can practise Grade 6 Science questions like these on Emerald, sorted by grade, subject and quarter, with the right answer shown after each try.
About the data: answers logged on Emerald between August and October 2026, counted per question with no personal details. The sample is small, so the percentages show patterns, not national results.